Explanation: Pictured above is the innermost of
Jupiter's Galilean satellites, Io,
superposed in front of the gas giant planet.
To the left of
Io
is a dark spot that is Io's own shadow.
A solar eclipse
would be seen from within the shadow spot on Jupiter.
Viewed from
planet Earth, similar shadows of Jupiter's large moons
can often be seen crossing
the giant planet's disk.
But during the next several months, the Galilean moons can also be seen
crossing in front
of each other as, for a while, their
orbits lie nearly edge-on
when viewed
by earthbound observers.
This true-color contrast-enhanced image
was
taken two years ago by the robot
spacecraft Cassini, as it passed Jupiter
on its way to Saturn in 2004.